I have an ESP-WROOM-32 and I'm using Arduino IDE to push code on it. My ESP is powered via 2 AA batteries and got one power supply problem.

It works well on new battery but after a bit, I will always get this error repeatedly:

ets Jun 8 2016 00:22:57

rst:0xc (SW_CPU_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT) configsip: 0, SPIWP:0xee clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00 mode:DIO, clock div:2 load:0x3fff0018,len:4 load:0x3fff001c,len:812 load:0x40078000,len:0 load:0x40078000,len:11584 entry 0x40078a60

Brownout detector was triggered

So, I know that it's possible to disable that feature in ESP32. My question is how to do it?

What I have done that didn't work:

Add this code in my Arduino IDE:

#include "soc/soc.h"
#include "soc/rtc_cntl_reg.h"
    WRITE_PERI_REG(RTC_CNTL_BROWN_OUT_REG, 0); //disable brownout detector    

Change Arduino\hardware\espressif\esp32\tools\sdk\sdkconfig with:

CONFIG_BROWNOUT_DET=                //previous was "=y"
CONFIG_BROWNOUT_DET_LVL_SEL_0=      //previous was "=y"
CONFIG_BROWNOUT_DET_LVL=           //previous was "=0"
  • 2
    Why do you want to disable it? It's there for a reason: Your batteries are too flat to reliably power the ESP-32.
    – Majenko
    Commented Aug 29, 2018 at 15:33
  • Because the manufacturer of the device told me to do it, but he's using ESP-IDF and I prefer to code with Arduino
    – Gazouu
    Commented Aug 29, 2018 at 15:42
  • What kind of batteries are you using?
    – Majenko
    Commented Aug 29, 2018 at 15:44
  • I'm using 2 AA batteries each 1.5V
    – Gazouu
    Commented Aug 29, 2018 at 16:05
  • 1
    I asked what kind, not what size. Alkeline? Zinc Carbon? NiMH?
    – Majenko
    Commented Aug 29, 2018 at 16:06

2 Answers 2


For me brownout issue was solved by removing the esp32 from Arduino IDE board manager + removing files from disk and use install procedure "Using Arduino IDE with the development repository" - https://github.com/espressif/arduino-esp32/

I guess it will use newer version of arduino-esp32 that has some brownout protection due to CONFIG_REDUCE_PHY_TX_POWER being activated by default. Also you should probably learn how to decrease wifi power + deep sleep for longer battery usage.


Maybe it's silly but I added a delay to my script before I got the error.

Serial.println("Delay 5s Brownout detector was triggered");

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